JP2012163028A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device of an internal combustion engine, which prevents the occurrence of defective injection by suppressing the drive change of a first fuel injection valve when the acceleration state from a first engine operational range exceeds the predetermined value.SOLUTION: The fuel injection device includes an in-cylinder direct-injection valve 17, an air intake passage injection valve 18, a fuel injection amount calculator A1, acceleration state detectors A1-A4, and a control unit ECU performing the control so that the total fuel injection amount at which the engine operating range is within the PI only injection range K1 is injected via the air intake passage injection valve, each divided fuel amount of a first fuel injection valve and a second fuel injection valve divided by the predetermined ratio α when the engine operating range is within DI+MPI injection range K2 is obtained, and the fuels of the respective divided fuel amounts are injected via a DI valve 17 and an MPI valve 18, respectively. The control unit performs the control so as to perform the injection via the DI valve 17 and the MPI valve 18 in the DI+MPI injection range K2 after the elapse of the predetermined waiting time tw when the acceleration state from the PI only injection range K1 to the DI+MPI injection range K2 exceeds the predetermined value, and enters the timer zone Et.

Description

  The present invention relates to a fuel injection device for an internal combustion engine in which a fuel injection valve is provided in each of a combustion chamber and an intake passage of the internal combustion engine, and in particular, a driving state of each fuel injection valve in accordance with a change in a load / rotation speed range of the internal combustion engine. The present invention relates to a fuel injection device for an internal combustion engine that switches between the two.

  As a fuel injection device employed in an internal combustion engine, an in-cylinder injection valve that injects fuel into a combustion chamber and an intake passage injection valve (port injection valve) that injects fuel into an intake passage are appropriately driven to be injected. 2. Description of the Related Art There is known a fuel injection device that injects fuel into an in-cylinder and intake passage. In a fuel injection device for an internal combustion engine having two fuel systems, an in-cylinder injection valve (also referred to as DI valve) and an intake passage injection valve (also referred to as MPI valve), the full load and full rotation of the fuel injection device of the internal combustion engine In some areas (hereinafter referred to as the entire operation area), there is a system in which both the in-cylinder injection valve and the intake passage injection valve are driven to inject. Furthermore, the entire operation range includes an MPI only injection region (injection mode) in which only the MPI valve injects, and a DI + MPI injection region (injection mode) in which both the in-cylinder injection valve and the intake passage injection valve are driven simultaneously to inject fuel ).

In each of these fuel injection regions, the fuel injection ratio between the in-cylinder injection valve (direct injection valve: DI valve) and the port injection valve (intake path injection valve: MPI) is set according to the rotation and load. For example, the MPI injection ratio is set larger than the DI injection ratio in the low rotation and low load range to stabilize the small quantity fuel injection, and the DI injection ratio is set larger than the MPI injection ratio in the high rotation and high load range. It facilitates high-load operation and ensures exhaust gas characteristics.
At this time, when changing both injection modes of the in-cylinder injection valve and the intake passage injection valve (DI valve and MPI valve), it is determined in consideration of the tip temperature of the DI injector, deposit generation requirements, etc. as judgment conditions for the change. is doing.

However, if the injection ratio changes frequently due to changes in the operating state, that is, the injection mode accompanying the change in the engine operating range, the injection operation overlaps before and after the change of the injection ratio, and the A / F feedback becomes unstable. There are concerns.
Therefore, when changing the injection ratio at the time of transition accompanying the change of the engine operating range, tailing processing (timer zone setting) is performed to suppress the change of the injection mode and then A / F feedback control. Is doing.

  In Patent Document 1 (Japanese Patent Application Laid-Open No. 4-237854), the in-cylinder injection valve injects fuel in the compression stroke when the load is low, and the port injection valve injects fuel into the intake port at the high load. A predetermined amount of fuel injection is added in the intake stroke in addition to the compression stroke injection so far by the in-cylinder injection valve on the predetermined low load side from the high load range where the injection in the intake pipe starts at the injection valve Thus, a fuel injection device is disclosed that prevents a misfire caused by a change in the engine operating range.

JP-A-4-237854

However, if the tailing process (timer zone setting) is performed uniformly in the case of simply changing the engine operating range (changing the injection mode), a sense of incongruity occurs in the driving operability, and in particular, a problem is likely to occur in the acceleration response. . In addition, in the case of patent document 1, although the misfire accompanying the change of an engine operating range is prevented, the tailing process is not mentioned.
Further, a preset DI valve is set in an operation region set by rotation and load used by a fuel injection device having two fuel systems including an in-cylinder injection valve and an intake passage injection valve (DI valve and MPI valve). When the fuel injection ratio of the MPI valve is changed by tailing each time the operating range is switched, an A / F mismatch during tailing occurs during acceleration operation in which the air amount changes suddenly. It is easy to do, and there is a tendency for knocking to occur, and improvement is desired.

  The present invention has been made based on the problems as described above, and the object of the present invention is that even if the degree of acceleration frequently fluctuates when the state of acceleration from the first engine operating range exceeds a predetermined value, An object of the present invention is to provide a fuel injection device for an internal combustion engine that can suppress the frequency of drive switching of the first fuel injection valve and prevent the occurrence of defective injection operation.

  The invention of claim 1 of the present application includes a first fuel injection valve for injecting fuel into a combustion chamber of an internal combustion engine, a second fuel injection valve for injecting fuel into an intake passage of the internal combustion engine, and an engine speed of the internal combustion engine. And a fuel injection amount calculating means for calculating a fuel injection amount according to the load, an acceleration state detecting means for outputting engine acceleration information, and a first operating range corresponding to the engine speed and the load. When in the engine operating range, all of the fuel injection amount of fuel is injected by the second fuel injection valve, and when in the second engine operating range on the high rotation high load side from the first engine operating range, the fuel injection is performed. The amount is divided at a predetermined ratio to obtain the divided fuel amounts of the first fuel injection valve and the second fuel injection valve, and the fuel of each divided fuel amount is injected by the first and second fuel injection valves. And a control means for controlling the second engine from the first engine operating range. When the acceleration state toward the operating region exceeds a predetermined value and enters a timer zone provided between the second operating region, the second engine operating region waits for the elapse of a predetermined waiting time. The first and second fuel injection valves are controlled so as to perform injection.

  According to a second aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first aspect, the control means accelerates the internal combustion engine when the level of acceleration during engine operation is divided into large, medium, and small sections. If the state is in an intermediate stage, it is considered that the acceleration state exceeds a predetermined value.

  According to a third aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first or second aspect, when the acceleration state of the internal combustion engine exceeds a predetermined value, the control means has a first acceleration injection ratio at a predetermined acceleration ratio. The second fuel injection valve is driven for injection.

  According to a fourth aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first aspect, at the time of deceleration from the second engine operating region toward the first engine operating region, only the second fuel injection valve is driven to inject. It is characterized by.

  According to a fifth aspect of the present invention, in the fuel injection device for an internal combustion engine according to any one of the first to fourth aspects, the acceleration information includes at least an intake air amount, an accelerator opening degree, and a throttle opening degree of the internal combustion engine. It is set by one or more.

The invention of claim 6 of the present application is the fuel injection device for an internal combustion engine according to claim 1, 2 or 3,
The predetermined ratio for dividing the fuel of the fuel injection amount is set so that the divided injection amount of the first fuel injection valve is larger than the divided injection amount of the second fuel injection valve.

  According to the first aspect of the present invention, when the acceleration state from the first engine operating range exceeds a predetermined value, when the timer zone is entered, the first and second in the second engine operating range after the elapse of the predetermined waiting time. Since the fuel injection valve performs the injection process, even if the degree of acceleration frequently fluctuates between the first engine operating range and the second engine operating range, the first waiting time elapses. Therefore, it is possible to suppress the drive switching frequency of the fuel injection valve, and it is possible to prevent the occurrence of defective injection operation due to the deposit generated around the injection port of the first fuel injection valve.

  According to the second aspect of the present invention, the first and second fuel injection valves are driven for injection after a predetermined waiting time has elapsed when the timer zone is entered in a moderate acceleration operation range where the acceleration state is moderate. Stable tailing can be performed in a wide acceleration operating range, the drive switching frequency of the first fuel injection valve can be suppressed, deposits can be prevented from being accumulated around the first fuel injection valve nozzle, and injection operation failure occurs. Can be reliably prevented.

  In the third aspect of the invention, when the acceleration state of the internal combustion engine exceeds a predetermined value, the first and second fuel injection valves are driven for injection at a predetermined acceleration injection ratio, so that the acceleration response is improved. .

  According to the fourth aspect of the present invention, only the second fuel injection valve is driven for injection when the internal combustion engine is decelerated, and deposits can be prevented from adhering to the first fuel injection valve during deceleration.

  The invention of claim 5 can easily determine the operating range where the acceleration information exceeds a predetermined position when at least one of the intake air amount, the accelerator opening, and the throttle opening exceeds a predetermined value.

  In the invention of claim 6, since the divided injection amount of the first fuel injection valve that injects the fuel into the combustion chamber is increased, the acceleration response is improved, and the unburned fuel to the exhaust passage at the time of overlap is improved. Release can be suppressed and useless fuel injection can be prevented.

1 is an overall configuration diagram of a fuel injection device for an internal combustion engine as an embodiment of the present invention. It is a block diagram of the control function part of the fuel-injection apparatus of the internal combustion engine of FIG. FIG. 3 is a characteristic explanatory diagram of an operation range setting map m1 used in the fuel injection device for the internal combustion engine of FIG. 1. FIG. 3 is a characteristic explanatory diagram of an operation range setting map m2 used in the fuel injection device for the internal combustion engine of FIG. 1. 4A and 4B are explanatory diagrams of the injection timing and ignition timing of the four cylinders used in the fuel injection device of the internal combustion engine of FIG. 1, wherein (a) shows a mode during cranking, and (b) shows a mode of a warm air or low load region. 4A and 4B are explanatory diagrams of the injection timing and ignition timing of the four cylinders used in the fuel injection device of the internal combustion engine of FIG. 1, wherein (a) shows a mode within two combustion cycles after acceleration at low load, and (b) shows a middle and high load range. Indicates the mode. FIG. 2 is an explanatory diagram of a change over time of an operating region during acceleration of the fuel injection device for the internal combustion engine of FIG. FIGS. 2A and 2B are explanatory views of changes over time in the fuel split ratio during driving of the fuel injection device of the internal combustion engine of FIG. 1, in which (a) shows tailing and (b) shows acceleration. It is a flowchart of the control processing routine which the fuel-injection apparatus of the internal combustion engine of FIG. 1 performs.

Hereinafter, a fuel injection device for an internal combustion engine according to a first embodiment of the present invention will be described.
FIG. 1 is an overall configuration diagram of an internal combustion engine (hereinafter referred to as an engine) 1 to which a fuel injection device for an internal combustion engine of the present invention is applied. In this engine 1, an intake manifold 4 and an exhaust manifold 5 are integrally coupled to the left and right side wall surfaces of the cylinder head 3 at the top of the engine body 2, and an intake passage Ri is connected to the intake manifold 4 and an exhaust passage Re is connected to the exhaust manifold 5. Is done.
As shown in FIG. 1, the engine 1 has four cylinders, and each cylinder has a combustion chamber 6 that forms a main part, and the intake passage Ri side of each combustion chamber 6 has a common surge via a corresponding intake manifold 4. It is connected to the tank 7.

  The surge tank 7 is connected to an air cleaner 9 via an intake duct 8, and an air flow meter 11 for obtaining intake air intake amount Qa information is attached to the air cleaner 9. A throttle valve 12 driven by an electric motor 121 is disposed in the intake duct 8. The throttle valve 12 has its opening degree controlled independently of the accelerator pedal 13 based on an output signal of an engine control device (hereinafter simply referred to as ECU) 14. Further, the throttle valve 12 is provided with a throttle opening sensor 28, and throttle opening θs information of the sensor is output to the ECU 14. In FIG. 1, the engine body 2 is provided with a water temperature sensor 43 that detects water temperature Tw information in the body, and the detection signal is output to the ECU 14.

The ECU 14 is composed of a digital computer, and includes a ROM 142, a RAM 143, a CPU 144, an input port 145, and an output port 146 connected to each other via a bidirectional bus 141, and has a control function described later.
The detection signals of the accelerator opening sensor 41 that generates an output proportional to the depression amount of the accelerator pedal 13 and the rotation speed sensor 42 that generates an output pulse representing the engine rotation speed Ne are input to the input port 145. Here, in the ROM 142 of the ECU 14, the value Qf of the fuel injection amount set corresponding to the operating state based on the engine load factor and the engine speed obtained by the accelerator opening sensor 41 and the engine speed sensor 42 described above. Further, a correction value corresponding to the engine coolant temperature Tw is mapped and stored in advance.

As shown in FIG. 1, an intake camshaft 32 and an exhaust camshaft 33 of a valve train system (only a part of which is shown) 31 interlocked with engine driving are arranged on the cylinder head 3 at the upper part of the engine body 2. When the shafts 32 and 33 are driven, an intake / exhaust valve (not shown) is driven to open and close, thereby opening and closing the intake port ip on the intake passage Ri side and the exhaust port ep on the exhaust passage Re side with respect to the combustion chamber 6. Intake and exhaust operations are performed.
The exhaust passage Re side extending from each combustion chamber 6 of the engine 1 is connected to the exhaust manifold 5, and the three-way catalyst 15 and the muffler 161 are sequentially connected to the downstream of the merging portion 501 of the exhaust manifold 5 through the exhaust pipe 16. ing.
As shown in FIG. 1, a cylinder injection valve (DI injection valve) 17 that is a first fuel injection valve for injecting fuel into the combustion chamber 6 is provided in the combustion chamber 6 of each cylinder. An intake passage injection valve (MPI injection valve) 18 that is a second fuel injection valve for injecting fuel is provided in the intake port ip (intake passage Ri side) in communication, and all cylinders are similarly configured.

Each of the injection valves 17 and 18 receives a fuel control signal from the ECU 14 via high and low pressure drive circuits (injector drivers) 37 and 38, and controls the injection amount of the fuel supplied from the fuel supply source to control the combustion chamber 6. , And injected into the intake port ip. Such a fuel supply system constitutes a main part of a fuel injection device that injects fuel into the cylinder and into the intake passage.
Here, the in-cylinder injection valve 17, which is a first fuel injection valve for injecting fuel into the combustion chamber 6, is connected to a common first fuel distribution pipe (common rail) 19, and this first fuel distribution pipe 19. Is connected to an engine-driven high-pressure fuel pump 21.
The discharge side of the high-pressure fuel pump 21 on the fuel supply side is returned to the suction side via an electromagnetic spill valve 22 that is a fuel pressure adjusting means. The smaller the opening of the electromagnetic spill valve 22, the higher the pressure of the high-pressure fuel pump 21. The amount of fuel supplied to the first fuel distribution pipe 19 is increased and the fuel supply is stopped when the first fuel distribution pipe 19 is fully opened. The valve receives a fuel pressure signal from the ECU 14 and supplies fuel of a predetermined fuel pressure to the in-cylinder injection valve 17. Supply.

  On the other hand, an intake passage injection valve 18, which is a second fuel injection valve for injecting fuel into the intake port ip, is connected to a common low-pressure side second fuel distribution pipe (common rail) 23, and the second fuel distribution pipe. 23 and the high-pressure fuel pump 21 are connected to a low-pressure fuel pump 25 via a common fuel pressure regulator 24. Further, the low pressure fuel pump 25 on the fuel supply side is connected to a fuel tank 27 via a fuel filter 26. The fuel pressure regulator 24 is configured to return a part of the fuel to the fuel tank 27 when the fuel pressure of the fuel discharged from the low pressure fuel pump 25 becomes higher than a predetermined set fuel pressure. The fuel pressure supplied to the injection valve 18 and the fuel pressure supplied to the high-pressure fuel pump 21 are prevented from becoming higher than the set fuel pressure.

As shown in FIG. 1, a fuel pressure sensor 43 that generates an output voltage proportional to the fuel pressure in the pipe is attached to the first fuel distribution pipe (common rail) 19, and the output voltage of the fuel pressure sensor 43 is 145 is input.
As shown in FIG. 1, in addition to the in-cylinder injection valve 17, a spark plug 29 is attached to the four combustion chambers 6 provided in the engine body 2.
An ignition unit 31 that outputs a high voltage is connected to the spark plug 29. The ignition unit 31 includes a timing control circuit (not shown), a high voltage power supply circuit, and an ignition coil. The ignition unit 31 generates a high voltage in the ignition coil in response to an ignition signal Tsp from the ECU 14 and performs an ignition process at a predetermined ignition timing.

  An air-fuel ratio sensor (hereinafter also referred to as an A / F sensor) 44 that generates an output voltage proportional to the oxygen concentration in the exhaust gas is attached to the exhaust manifold 5 located upstream of the exhaust passage Re shown in FIG. The detection signal of the A / F sensor 44 is input to the input port 145. The A / F sensor 44 is a linear air-fuel ratio sensor that generates an output voltage proportional to the air-fuel ratio, but instead of this, it is determined whether the air-fuel ratio is rich or lean with respect to the stoichiometric air-fuel ratio. An O2 sensor 45 that detects on / off information downstream of the original catalyst 15 may be used instead.

  As shown in FIG. 1, the three-way catalyst 15 can purify the exhaust gas by oxidizing CO and HC in the exhaust gas and reducing NOx in the vicinity of the stoichiometric air-fuel ratio (stoichio). A catalyst (platinum, rhodium, palladium, etc.) carried on a carrier (not shown) of the three-way catalyst 15 is not activated and does not have a purification function unless it reaches a certain temperature (high temperature). Therefore, in the fuel injection device of the engine 1, when the engine 1 is cold-started, a warm-air increasing operation described later is performed so as to activate the three-way catalyst 15 at an early stage.

  Whether or not the three-way catalyst 15 is activated can be determined by detecting the oxygen concentration in the exhaust on the exhaust downstream side of the three-way catalyst 15. This is because an oxygen sensor 45 provided on the downstream side of the three-way catalyst 15 uses an output of a region indicating activation of the three-way catalyst 15, and an increase in the outlet side exhaust temperature (oxidation reaction) occurs. It is judged that this is due. Further, it is possible to estimate the temperature of the three-way catalyst by detecting the water temperature of the engine cooling water or the oil temperature of the engine oil, and determine the activation of the three-way catalyst 15 based on the result.

  Next, the control function of the ECU 14 will be described. As shown in FIG. 2, the ECU 14 uses the in-cylinder injection valve (first fuel injection valve) 17 and the intake passage injection valve (second fuel injection valve) to inject the fuel of the injected fuel amount Qf set according to the operation information. ) 18 is divided by a predetermined ratio α, and the fuel injection control means A1 that controls the fuel injection of each of the divided injection amounts Qf1 and Qf2 and the ignition sequence (see FIG. 5B) are 1-3. Functions of ignition timing control means A2 for controlling the ignition timing Tsp of the ignition plug 21 of each cylinder 4-2 and engine speed control means A3 for controlling the engine speed Ne are provided.

  Here, the fuel injection control means A1 presets an operation range map m1 shown in FIG. In this operating range map m1, the engine operating range corresponding to the engine speed (engine speed) Ne and the load (accelerator pedal opening) θa is the low output side below a predetermined load θa1 and the rotational speed Ne1, A low load range EL including an idle operation range (ID range), a medium output side medium load range EM in a load θa2 and a rotational speed range Ne2 that is larger by a predetermined amount than the low load range EL, and a medium larger than the medium load range EM This is divided into a high load region EH on the output side.

  After that, the low load range EL including the idling operation range (ID range) is set as the MPI only injection range K1 in which injection is performed only by the intake passage injection valve 18. Further, on the high output side exceeding the MPI-only injection range K1, the high load / rotational speed range EM, EH is set as the DI + MPI injection range K2 in which both the in-cylinder injection valve 17 and the intake passage injection valve 18 inject. Here, the low load region EL and the middle, high load / rotational speed regions EM, EH are divided by the set load line L1. Here, the DI + MPI injection region is set to be relatively large, and the operation region in which priority is given to the acceleration characteristics in the medium and high load / rotational speed regions EM, EH is expanded.

Further, a tailing processing area Et, which will be described later, is set with a predetermined width between the MPI only injection area K1 and the DI + MPI injection area K2, that is, at a position overlapping the set load line L1.
The fuel injection control means A1 having the operation range map m1 as shown in FIG. 3 is a low load control unit (also referred to as an MPI only injection control unit) A1- that performs injection control of the MPI only injection range K1, which is the low load range EL. 1, middle, high load rotation speed range EM, during the injection control of DI + MPI injection range K2 which is EH, high load control unit (also referred to as DI + MPI injection control unit) A1-2, in the ID range at cold start In order to promote warm-up, a start control unit A1-3 that controls the intake passage injection valve 18 to perform fuel injection of a predetermined warm-up fuel amount, and an acceleration value (δθan) within the MPI-only injection region that is the low load region EL = Θan−θan−1) is divided into large, medium, and small acceleration determination values δθaH, δθaM, and δθaL, and an acceleration control unit A1-4 that performs acceleration increase injection control according to the current acceleration value δθan.

  Here, in the MPI only region K1, which is the low load region EL, the low load control unit A1-1 determines the fuel injection amount Qf corresponding to the engine speed Ne and the accelerator pedal depression amount θa in a predetermined steady fuel amount calculation map ( Obtained from (not shown). Further, MPI-only injection control (see FIG. 5B) in which fuel of this fuel injection amount Qf is injected only by the intake passage injection valve (MPI valve) 18 of each cylinder is executed, and the engine 1 rotates in a low load region. Stabilize.

  The medium / high load control unit (DI + MPI injection control unit) A1-2 performs fuel injection in accordance with the engine speed Ne and the accelerator pedal depression amount θa in the DI + MPI injection region K2 including the medium / high load rotation speed regions EM and EH. The amount Qf is obtained from a predetermined steady fuel amount calculation map (not shown). Further, the fuel of the fuel injection amount Qf is injected by DI + MPI injection control (see FIG. 6B) in which both the cylinder injection valve 17 and the intake passage injection valve 18 inject. At this time, for example, 6 (α): 4 (1-α) is set so that the preset distribution ratio α, for example, the injection amount Qf1 of the in-cylinder injection valve 17 is larger than the injection amount Qf2 of the intake passage injection valve 18. In order to stabilize the rotation of the engine 1 in the DI + MPI injection range, which is the middle and high load speed ranges EM, EH.

Further, the start control unit A1-3 performs fuel injection during cranking in the start control region (ID region: see FIG. 2) before the cranking is completed. Here, a predetermined starting fuel amount Qfs is obtained by a predetermined cold starting fuel amount calculation map (not shown). Further, as shown in FIG. 5 (a), the fuel with the injection amount ½ of the starting fuel amount Qfs is divided into divided injection timings I _{1 and} I ₂ of 2 degrees per combustion cycle (every 360 degrees). Simultaneous injection is performed on all cylinders. At this time, the ignition timing control means A2 performs all cylinder simultaneous ignition at the ignition timing (Tsp) every 180 degrees, cranking is performed, and early start is performed.

  Further, in the start control region (ID region) after cranking, the start control unit A1-3 sets the fuel injection amount Qfd1 at the time of cold start at the time of cold start, and after warming up after the warming up. The fuel injection amount Qfd2 at the time of ID is read, and MPI-only injection control (see FIG. 5B) for injecting the fuel of the fuel injection amount Qfd at the time of ID only by the intake passage injection valve 18 of each cylinder is executed. To stabilize the rotation in the idle operation range.

Next, the acceleration control unit A1-4 performs acceleration as the amount of change in the longitudinal control cycle of the load θa, which is the accelerator pedal depression amount, while the engine 1 is operating in the MPI-only injection region K1, which is the low load region EL. Acc (= θa _(n) −θa _(n−1) ) is calculated, and when this acceleration Acc is determined to be greater than or equal to a predetermined value Acc1 (preliminarily set as a value capable of determining the intention to accelerate), acceleration increasing injection Then, when entering the tailing process area Et overlapping the set load line L1, the tailing process and the acceleration operation process are performed as follows according to the degree of acceleration.
In the tailing process here, as shown in FIG. 3, when the operating region moves from the MPI-only injection region K1 to the DI + MPI injection region K2, the acceleration Acc is obtained from the change in the accelerator pedal opening θa at the time of the change.

Here, as shown in FIG. 7, the level of the acceleration Acc, which is the degree of change in the accelerator pedal opening θa when the vehicle is running, is divided into roughly equal ratios of large, medium, and small as shown in FIG. Is set.
Here, when the state of the determined acceleration (see symbols a1 and a2) exceeds a predetermined value, that is, when the degree of acceleration is at a medium level or above, it is considered that the state of acceleration exceeds a predetermined value. The Such a case is shown as a2 in FIG.

  Thus, when the acceleration state exceeds a predetermined value, after waiting for the elapse of the waiting time tw for the tailing process, after the elapse of the time point ta2 in FIG. 8A, the DI + MPI injection region K2 Control is performed so that injection is performed by the in-cylinder injection valve (first fuel injection valve) 17 and the intake passage injection valve (second fuel injection valve) 18. In FIG. 8 (a), tailing is performed from the acceleration determination time ta1, and the injection ratio α between the DI valve (non-actuated) and the MPI valve is changed stepwise from 0:10 to 7: 3, By entering the DI + MPI injection region K2 at the time point ta2, tailing is finished, and the flow of control to return to the normal injection ratio 6: 4 in the DI + MPI injection region K2 is schematically shown.

  In FIG. 8 (a), one combustion cycle BS is indicated by a rectangular frame, and fuel of a fuel injection amount Qf calculated in accordance with the operating state θa, Ne of the engine 1 in one combustion cycle BS is set to a predetermined injection ratio. α, that is, the ratio values (0 to 10) divided into the respective divided injection amounts of the DI valve and the MPI valve are described separately in the upper and lower directions.

Next, if it is determined that the level of acceleration Acc (the level of acceleration) is high, and it is determined that it is at the high level indicated by reference numeral a1 in FIG. 2, the tailing process described above is shown in FIG. 8B. Thus, the control flow of entering the acceleration control process is schematically shown.
In this case, the acceleration fuel amount Qfa at the time of acceleration corresponding to the operation information θa, Ne is calculated from the acceleration determination time ta1 until the DI + MPI injection region K2 is entered, and the DI valve is operated at the acceleration injection ratio α (7: 3). The MPI valve is operated for fuel injection. When the time point ta3 is reached in the DI + MPI injection region K2, if the level (acceleration level) remains large, the acceleration state is continued as indicated by a two-dot chain line in FIG. When the large state is left, the normal injection ratio 6: 4 in the DI + MPI injection region K2 is returned to perform the injection operation.

Next, the operation of the fuel injection device of the engine 1 according to the embodiment of the present invention will be described along the fuel injection control process shown in FIG. Here, in the main routine (not shown) prior to the fuel injection control routine, various operation information data are taken in simultaneously with the main key switch being turned on and stored in a predetermined storage area.
Moreover, the routine reaches step s1 of the fuel injection control routine at a predetermined timing when it is detected that the engine 1 has entered cranking at the time of start.

In step s1, engine operation information such as engine speed Ne, fuel accelerator opening θa, throttle opening θs, water temperature Tw, air-fuel ratio A / F, oxygen concentration O _{2, and the} like in the fuel injection control are determined according to each operation information. The set value data is taken in and stored as the latest data, and the process proceeds to step s2.

Here, it is determined whether or not the engine is cranked, and the process proceeds to step s3. When step s3 is reached during the cranking process, the fuel injection amount Qfc at the time of cold start or ID after warm-up is read, and as shown in FIG. 5A, the injection of the fuel amount Qfc at the start is performed for one combustion cycle. The injection is divided into two injection times I _{1 and} I ₂ (= 1 / 2Qfc) per BS (every 360 °) and simultaneously injected into all cylinders. The spark plug 29 performs all cylinder simultaneous ignition every 180 degrees and When the ranking is completed, the process returns to steps s1 and s2, and proceeds to step s4.
In step s4, it is determined whether the DI + MPI injection region K2 is in the middle and high load regions EM, EH. If yes, the process proceeds to step s7, and if no, the process proceeds to step s5. In step s5, it is determined whether or not the MPI is in the MPI-only area K1 of the low load area EL.

  In step s7, a fuel injection amount Qf corresponding to the current engine speed Ne and accelerator pedal depression amount θa is obtained from a fuel amount calculation map (not shown). When step s7 is reached as the low load region EL from step s6, the fuel injection amount in the MPI only injection region K1 shown in FIG. In other words, only the MPI valve executes the injection drive at Qf (: 10 (α)) to stabilize the rotation of the engine 1 during traveling at a low load. On the other hand, when reaching here as being the DI + MPI injection region K2 of the middle and high load regions EM, EH, the injection amount in the DI + MPI injection region shown in FIG. 6B is set, that is, the in-cylinder injection valve 17 Is set such that the injection amount Qf is 6 (α) and the injection amount Qf of the intake passage injection valve 18 is 4 (1-α). In this set state, injection in the DI + MPI injection region is performed to stabilize the rotation of the running engine, and the process returns to the main routine.

  Next, when step s6 is reached from step s5, acceleration determination in the low load region EL is made at that time. It is determined whether or not the current acceleration value Acc (= θan−θan−1), which is the difference between the accelerator opening of the previous time and the current time, exceeds a predetermined acceleration determination value Acc1. If it exceeds s7, the routine proceeds to step s8 as acceleration in the low load range EL.

When the acceleration determination is made and step s8 is reached, whether the acceleration here is a medium acceleration level from the MPI only region K1 of the low load region EL to the DI + MPI injection region K2 of the high load region EM, EH (see FIG. 7). Judgment is made, that is, it is judged whether or not the acceleration is indicated by reference signs a1 and a2 in FIG. 2, and the process proceeds to step s9 with Yes and proceeds to step s10 with No.
Steps s9 and s11 are medium acceleration levels, and tailing processing is performed as shown in FIG. That is, the injection rates of the DI valve 17 and the MPI valve 18 are changed in stages from α to (0/10 to 7/3) over time from the acceleration determination time ta1, and the waiting time tw for tailing processing is changed. After waiting for the progress, the process proceeds to step s12, where tailing is stopped and the process returns to the main routine.

  At this time, since the operation range has reached the DI + MPI injection range K2 in the middle and high load range EM, EH, the step reaches step s7 from step s4 in the next control cycle, as shown in FIG. 6 (b). Further, the injection amount Qf of the in-cylinder injection valve 17 is set to a ratio of 6 (α) and the injection amount Qf of the intake passage injection valve 18 is set to a ratio of 4 (1−α). In this set state, injection in the DI + MPI injection region is performed to stabilize the rotation of the running engine, and the process returns to the main routine.

On the other hand, when it is determined that the level of acceleration Acc (the level of acceleration) in step s8 is large and step s10 is reached, it is first determined whether or not the vehicle is decelerating-Acc. Furthermore, the process proceeds to step s13 during acceleration.
When steps s15 and s16 are reached during deceleration, the tailing process is stopped, only the MPI valve 18 is changed, that is, the injection ratio α is changed to the MPI valve 18 (α: 10), and the injection operation is started in the MPI-only injection region K1. As a result, it is possible to prevent the occurrence of defective injection operation due to deposits occurring around the injection hole of the DI valve 17 during deceleration, and the process returns to the main routine.

Assume that steps s10 to s13 and s14 are reached.
Here, as shown in FIG. 8B, the acceleration control process under a high load is started. In this operating range, the acceleration fuel amount Qfa at the time of acceleration corresponding to the operating information θa and Ne is calculated from the acceleration determination time ta1 to the DI + MPI injection range K2, and DI is calculated at the acceleration injection ratio α (7: 3). The process of fuel injection operation of the valve and the MPI valve is repeated.

  When the time point ta3 is reached in the DI + MPI injection region K2, if the level (stage of acceleration) remains large, the process returns to step s8, and the acceleration state is changed as shown by a two-dot chain line in FIG. If it continues and leaves the state of a large level, it will progress to No side and will return to a main routine. At this time, since the current operation range has reached the DI + MPI injection range K2 of the high load range EM, EH, the step reaches step s7 from step s4 in the next control cycle, and as shown in FIG. The injection amount Qf of the inner injection valve 17 is set to 6 (α) and the injection amount Qf of the intake passage injection valve 18 is set to a ratio of 4 (1−α). In this setting state, injection is performed in the DI + MPI injection region. Stabilize the running engine and return to the main routine.

As described above, in the first embodiment, when entering the timer zone, the DI valve 17 and the MPI valve 18 perform the injection in the DI + MPI injection region K2 after the elapse of the predetermined waiting time tw. Therefore, the MPI only injection region K1 and the DI + MPI injection Even if the degree of acceleration frequently fluctuates with the region K2, it is possible to suppress the drive switching frequency of the first fuel injection valve by waiting for the elapse of the predetermined waiting time, and deposit around the injection port of the DI valve 17 It is possible to prevent the occurrence of defective injection operation due to the occurrence of.
Further, when steps s9 and s11 are reached in a moderate acceleration operation region where the acceleration state is moderate, tailing processing (timer zone Et) is entered, and DI valve 17 and MPI valve 18 are injected after a predetermined waiting time tw has elapsed. Since it is driven, stable tailing can be performed in a moderate acceleration operating range, the frequency of switching the drive of the DI valve 17 can be suppressed, deposits can be prevented from being accumulated around the injection port of the DI valve 17, and an injection operation failure occurs. Can be reliably prevented.

Further, when the acceleration state Acc of the engine 1 exceeds the predetermined value Acc1, the DI valve 17 and the MPI valve 18 are driven to be driven at a predetermined acceleration injection ratio α (see steps s9 and s13), so that the acceleration response is Improved.
Further, as shown in steps s15 and s16, when the engine 1 is decelerated, only the MPI valve 18 is driven for injection, and deposits can be prevented from adhering to the DI valve 17 during deceleration.
Furthermore, when accelerating in the MPI-only injection region K1, the divided injection amount of the DI valve 17 that injects fuel into the combustion chamber 6 increases (see FIG. 8 (a)). It is possible to suppress the release of unburned fuel to the exhaust passage at the time of lap and to suppress useless fuel injection.

As described above, in the first embodiment, a relatively narrow fuel injection region such as a low load / low rotation speed region is set as an only injection region. However, depending on the case, as shown in a map m2 shown in FIG. The medium load / low / medium rotational speed range may be set as a relatively wide injection range, and only the high load / high rotational speed range may be set as the DI + MPI injection range. In this case as well, the same effects as those of the first embodiment can be obtained. In particular, as shown in the map m2 shown in FIG. 4, the MPI-only injection region (low, medium load operation region) is relatively wide, and during acceleration during the operation. Therefore, the switching at the threshold line L1 at which the fuel injection mode is switched is suppressed, and the uncomfortable feeling due to the excessive change of the driving range can be reduced.
Further, during the acceleration control process in steps s13 and s14 in the first embodiment, as the deformation control process, the control is performed on the assumption that the degree of acceleration fluctuates frequently as shown in FIG. May be added.

That is, in this modified example, as shown in FIG. 7, when accelerating in the MPI-only injection range K1, when the operating range reaches the time point ta4, a timer (not shown) is set and set to the intermediate level. If the return time δt is smaller than the set value δt1, the operating range is regarded as the MPI only injection range K1, and the DI valve You may control so that an action | operation may be suppressed. In this case, since the injection of minute fuel from the DI valve is suppressed, it is possible to suppress deposits from adhering to the DI valve.
The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

1 Engine (fuel injection device)
6 Combustion chamber 11 Air flow meter 17 DI valve (in-cylinder injection valve: first fuel injection valve)
18 MPI valve (intake channel injection valve: second fuel injection valve)
28 Throttle opening sensor 31 Ignition device 37 High pressure drive circuit (injector driver)
38 Low voltage drive circuit (Injector driver)
41 Accelerator opening sensor (driving information detection means)
tw waiting time α predetermined ratio θa load A1 fuel injection amount calculation means A1-4 acceleration state detection means Acc acceleration information Et timer zone ECU control means K1 MPI only injection area K2 DI + MPI injection area Ne engine speed Qf fuel injection quantity

Claims (6)

A first fuel injection valve that injects fuel into the combustion chamber of the internal combustion engine, a second fuel injection valve that injects fuel into the intake passage of the internal combustion engine, and fuel according to the engine speed and load of the internal combustion engine 1 A fuel injection amount calculating means for calculating an injection amount; an acceleration state detecting means for outputting engine acceleration information; and the engine operating range in a first engine operating range corresponding to the engine speed and load. All fuel of the fuel injection amount is injected by the second fuel injection valve, and the fuel injection amount is divided by a predetermined ratio when the fuel injection amount is in the second engine operation region on the high rotation and high load side from the first engine operation region. Control means for determining the divided fuel amounts of the first fuel injection valve and the second fuel injection valve and controlling the fuel of the divided fuel amounts to be injected by the first and second fuel injection valves; , And
The control means is a case where the acceleration state from the first engine operating range toward the second engine operating range exceeds a predetermined value and enters a timer zone provided between the second operating range, A fuel injection device for an internal combustion engine, wherein control is performed so as to perform injection by the first and second fuel injection valves in the second engine operating range after waiting for a predetermined waiting time.   In the case where the acceleration means during engine operation is divided into large, medium, and small stages, and the acceleration state of the internal combustion engine 1 is in a medium stage, the acceleration state exceeds a predetermined value. The fuel injection device for an internal combustion engine according to claim 1, characterized in that:   3. The control device according to claim 1, wherein when the acceleration state of the internal combustion engine exceeds a predetermined value, the control means drives the first and second fuel injection valves at a predetermined acceleration injection ratio. A fuel injection device for an internal combustion engine.   2. The fuel injection device for an internal combustion engine according to claim 1, wherein only the second fuel injection valve is driven for injection during deceleration from the second engine operating range toward the first engine operating range.   5. The internal combustion engine according to claim 1, wherein the acceleration information is set based on at least one of an intake air amount, an accelerator opening, and a throttle opening of the internal combustion engine. Fuel injection device.   The predetermined ratio for dividing the fuel of the fuel injection amount is set so that the divided injection amount of the first fuel injection valve is larger than the divided injection amount of the second fuel injection valve. Item 4. The fuel injection device for an internal combustion engine according to Item 1, 2 or 3.

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